Portable power bank



FIG. 1 is a top left perspective view of the portable power bank showing my new design:

FIG. 2 is bottom right perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The broken lines shown in the drawings depict portions of the portable power bank which form no part of the claimed design. 

CLAIM The ornamental design for a portable power bank, as shown and described. 